This proposal will attempt to carry out a short-term (four-year), longitudinal study of 138 children with a psychotic parent, genetically at high risk for future psychosis, and 184 children at low risk, with a physically ill or normal parent. These three groups, comprising a total of 322 children and 205 parents, have been already intensively investigated through a wide range of psychiatric, psychological, social, experimental, psychophysiological, and physical measures, subsequent to which each child subject (experimental and control) was scored on the level of adjustment, the amount of risk to which his inheritance, development, and environment had exposed him, and his testable vulnerability (or invulnerability) as indicated by certain sensitive response measures. Predictions were made on each case with regard to expectancy and type of disturbance in the immediate, near, and distant future. (Psychotic breaks have already occurred in four Ss in the high risk, high vulnerability group and a variety of lesser disorders in others.) These disturbances (as well as the absence of expected disturbances) will be correlated with the nature of the parental psychosis and its relapses and remissions, the socio-economic and ethnic characteristics of the family, the age, sex and risk-vulnerability status of the subjects and their phase of development, and the preventive efficacy of interventions in one-third of the subjects at risk.